Cause:
The current default configuration of all StruxureWare Data Center Expert is that the system comes with a pre-installed 25 node license key. The Virtual Machine or VM version shows this same 25 node license key in the user interface however until activated, will only allow 5 nodes to be added to the system.

Resolution:
This is by design. It was done so APC did not need to add a 5 node key to just this one version. Once activated, the rest of the nodes can be used.